People spend majority of the time daily in enclosed spaces, like cars, buses, bedrooms, offices, schools, workshops, ship cabins and compartments, etc., and are increasingly aware that the invisible harmful chemicals existing in the air of enclosed spaces are threatening their health and impacting their life quality. US EPA estimates Indoor air pollution is two to five times worse (sometimes a 100× worse) than the air outdoors. For examples, chemicals emitted from vehicle engine exhaust, gas stoves, fireplaces, household paints, cleaning and pesticide sprays, plastic wallpapers, polymer foams, adhesives, furniture, carpets, as well as bad odors from kitchen waste, bathrooms, toilets, pets, smokes, diesel and gasoline fumes, etc., often include those harmful substances like formaldehyde, benzene, toluene, xylene, carbon monoxide, nitric oxide, nitrogen dioxide, ammonia, sulfur dioxide, hydrogen sulfide, alcohols, chlorine, propene, butadiene, acetone, mercaptans, etc. These chemicals can easily accumulate to higher concentration in the enclosed spaces due to restricted ventilation. Exposure to those chemicals can cause common ailments such as headaches, coughs, nausea, dizziness, fatigue, depression; prolonged inhaling can cause permanent damage to the lungs, liver, brain and other body systems. Children are more susceptible to environmental exposures than adults and, because of their developing systems, particularly vulnerable to the toxic chemicals' detrimental effect on their growth. For example, benzene, often found in new carpets, is a known cause of leukemia; formaldehyde, widely used in insulation foam, disinfectants and pressed kitchen cabinets, is classified as a human carcinogen by International Agency for Research on Cancer (IARC); 1,3-butadiene, often found in automobile exhaust and cigarette smoke, is also listed as a known carcinogen by the Agency for Toxic Substances Disease Registry and the US EPA. Clearly there is a need to tackle this indoor air pollution problem which affects millions of people's health.